<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <div>
            aaaaaa
            <p>
                bbbbbb
            </p>
        </div>
    </div>

    <script>
        var $app = document.querySelector('#app');
        // 获取标签和文本
        console.log('innerHTML=', $app.innerHTML);
        // 只获取文本
        console.log('innerText=', $app.innerText);
    </script>
</body>

</html>